The present invention relates to a process for making fibrous polyolefin products by melt spinning and products thereof.
While fibrous polyolefins, particularly polypropylene, have been found to possess certain characteristics superior to other synthetic fibrous materials, it is generally recognized that fibrous polyolefins have peculiarities not possessed by other synthetic fibers, which often limit the processability of such materials and limit the end uses to which the products can be applied. For example, the processability limitations result in relatively low extrusion, spinning and wind-up speeds. Often high breakout rates are experienced and further processing of the spun fibers is limited, to the extent that inconsistent texture, broken filaments, lack of color control and difficult in knitting and weaving are often encountered. The products produced by melt spinning polyolefins also have relatively high spun denier, low tenacity, low birefringence, high elongation, high boiling water shrinkage, low modulus of elasticity, as well as other limitations which limit the uses to which the fibrous materials can be applied. It is also recognized that polyolefin fibers cannot generally be utilized in their as-spun state, i.e., with little or no further processing.
It is therefore an object of the present invention to provide an improved process for producing fibrous polyolefin products which overcomes the above-mentioned and other disadvantages of prior art processes and improved fibrous polyolefin products which overcome the above-mentioned and other disadvantages of prior art products. Another object of the present inventoion is to provide a process for producing melt spun, fibrous polyolefin products and fibrous polyolefin products which can be utilized with little or no additional processing. Another object of the present invention is to provide an improved process for producing fibrous polyolefin products which can be carried out at relatively high speeds, particularly higher speeds of extrusion, spinning and wind-up. Another and further object of the present invention is to provide an improved process for producing fibrous polyolefin products which result in products of a low spun denier with consequent lower draw ratios and improved products thereof. Yet another object of the present invention is to provide an improved process for producing fibrous polyolefin products of improved processability, particularly reduced breakout, higher draw ratios, higher and more constant twist levels during false twist texturing, better ease of handling in knitting, weaving, etc., improved color control and improved products thereof. A still further object of the present invention is to provide fibrous polypropylene products having a low spun denier, high tenacity, high birefringence, low elongation, low boiling water shrinkage, high modulus of elasticity and/or high break strength. A still further object of the present invention is to provide fibrous polyolefin products of improved coherency and/or bulkiness. These and other objects of the present invention will be apparent from the following description.